This proverb "Prevention is better than cure" advises us to be cautious and careful to detect and root out the cause of a trouble before it overtakes us and gets aggravated. This proverb, on the face of it, applies to physical health.
It is good to see a doctor when we are sick, but it would be still better not to fall sick at all by taking precautionary and preventive measures, well in advance. If we are a little cautious at the time of change of season, we may not fall sick. But if we are indifferent or negligent, the illness may attack us and its cure may prove costly or, perhaps even impossible.
The truth contained in this proverb holds well in any sphere of life. Neglecting our studies throughout the year and then studying with a nervous heart when exams are around the corner indicates the truth in this proverb.
Thus, this proverb reminds us that most of our misfortunes can be avoided only if we see the trouble and take a little trouble to ward it off as early as possible.